If you don’t know who GG Allin is (was), you have a fun journey of discovery ahead. He was a singer of sorts I suppose, but his Wikipedia entry puts it a bit better:

Allin is best remembered for his notorious live performances that typically featured wildly transgressive acts such as Allin defecating and urinating onstage, rolling in feces and often consuming excrement, committing self-injury, performing naked, and committing violent actions toward the audience